The invention relates to a device for erecting flat-folded tubular blanks, destined for use in packing machines.
In the prior art, various types of articles are packed in containers obtained from cardboard blanks. These blanks are supplied in a flat-folded tubular form and must therefore be opened-out to full volume so that articles to be packed can be inserted therein.
Packing machines therefore have to be provided with suitable devices for opening and folding the tubular blanks predisposed initially in flat-folded form in a store. The tubular blanks are opened and folded along prefixed preferential folding lines, usually known as score lines, so that they can receive articles in a vertical or horizontal direction.
Known erecting devices, made according to various operating modalities, do not fully satisfy the requirements of effectiveness of use, high operating velocity and functional simplicity required by cartoning machines. The prior art in particular comprises devices which predispose the tubular blank to be opened on a work plane and open it by means of special folding organs which cause the rotation of the sides of the blank about a respective folding line. This rotation arranges the adjacent sides of the tubular blank substantially at right-angles.
A drawback noted in prior-art devices consists in the fact that the rotation of the folding organs is often not able to ensure stable forming of the tubular blank in open configuration. The fold made about the score line is generally subject to an elastic return effect which tends to return the tubular blank at least partially into the flattened shape.